Working As a Physicist Flashcards
What is the scientific process?
Ask a question
Create a suggestion (explanation) for the answer
hypothesis
Carry out a test to provide evidence
What are the 7 SI base units?
Mass-kg
Length-m
time- s
current- A
temperature- kelvin
amount of substance- mol
luminous intensity- cd (candela)
What is the independent variable?
The variable you change
What is the dependent variable?
The variable you measure
What are the control variables?
Variables that must stay the same
What is absolute uncertainty?
the total uncertainty for a measurement
What is the percentage uncertainty?
The uncertainty as a percentage of the measurement.
uncertainty/ measurement taken x 100
How can you reduce the percentage uncertainty?
Measuring larger values
What is the smallest uncertainty you can have?
The uncertainty caused by the resolution of the equipment
(+ or - 1/2 of the resolution of equipment)
How do you calculate the uncertainty of a mean?
The mean value - the value of largest difference
Or
Half the range / the mean
How do you combine uncertainties when adding or subtracting data?
You add the uncertainty of the pieces of data together
How do you combine the uncertainty when multiplying or dividing data?
You add the PERCENTAGE uncertainties of the pieces of data together
How do you combine the uncertainties when raising to a power?
Multiply the PERCENTAGE uncertainty by the power
What is precision?
When the spread of the data is small
What is accuracy?
When the result is close the the true value
What are systematic errors?
Errors that shift all of the results by the same value.
What causes systematic errors?
The equipment not being set up properly or being faulty
What are random errors?
Errors where the results vary from test to test
What causes random errors?
Changes to the control variable or the way that you measure the data
How do you prevent random errors?
More repeats
Using an apparatus with better resolution
Use a computer/ data logger
What is uncertainty?
The interval in which the true value lies within
How to improve the validity of results?
Control more variables
Use more precise measuring equipment
Obtain more results
How to reduce systematic errors
Calibrating equipment
Read results at eye level to remove parallax error
